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Move phi-node generation into a helper that measures the liveness of each incoming edge. Factorial test now succeeds.

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This commit is contained in:
Graydon Hoare 2010-11-12 14:51:11 -08:00
parent 2ff0662eae
commit 0578978495
1 changed files with 64 additions and 43 deletions
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107
src/comp/middle/trans.rs
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@ -584,18 +584,15 @@ impure fn trans_binary(@block_ctxt cx, ast.binop op,
auto rhs_cx = new_sub_block_ctxt(cx, "rhs");
auto rhs_res = trans_expr(rhs_cx, b);
auto next_cx = new_sub_block_ctxt(cx, "next");
rhs_res.bcx.build.Br(next_cx.llbb);
auto lhs_false_cx = new_sub_block_ctxt(cx, "lhs false");
auto lhs_false_res = res(lhs_false_cx, C_bool(false));
lhs_res.bcx.build.CondBr(lhs_res.val,
rhs_cx.llbb,
next_cx.llbb);
auto phi = next_cx.build.Phi(T_bool(),
vec(lhs_res.val,
rhs_res.val),
vec(lhs_res.bcx.llbb,
rhs_res.bcx.llbb));
ret res(next_cx, phi);
lhs_false_cx.llbb);
ret join_results(cx, T_bool(),
vec(lhs_false_res, rhs_res));
}
case (ast.or) {
@ -605,18 +602,15 @@ impure fn trans_binary(@block_ctxt cx, ast.binop op,
auto rhs_cx = new_sub_block_ctxt(cx, "rhs");
auto rhs_res = trans_expr(rhs_cx, b);
auto next_cx = new_sub_block_ctxt(cx, "next");
rhs_res.bcx.build.Br(next_cx.llbb);
auto lhs_true_cx = new_sub_block_ctxt(cx, "lhs true");
auto lhs_true_res = res(lhs_true_cx, C_bool(true));
lhs_res.bcx.build.CondBr(lhs_res.val,
next_cx.llbb,
lhs_true_cx.llbb,
rhs_cx.llbb);
auto phi = next_cx.build.Phi(T_bool(),
vec(lhs_res.val,
rhs_res.val),
vec(lhs_res.bcx.llbb,
rhs_res.bcx.llbb));
ret res(next_cx, phi);
ret join_results(cx, T_bool(),
vec(lhs_true_res, rhs_res));
}
}
@ -722,6 +716,48 @@ impure fn trans_binary(@block_ctxt cx, ast.binop op,
fail;
}
fn join_results(@block_ctxt parent_cx,
TypeRef t,
vec[result] ins)
-> result {
let vec[result] live = vec();
let vec[ValueRef] vals = vec();
let vec[BasicBlockRef] bbs = vec();
for (result r in ins) {
if (! is_terminated(r.bcx)) {
live += r;
vals += r.val;
bbs += r.bcx.llbb;
}
}
alt (_vec.len[result](live)) {
case (0u) {
// No incoming edges are live, so we're in dead-code-land.
// Arbitrarily pick the first dead edge, since the caller
// is just going to propagate it outward.
check (_vec.len[result](ins) >= 1u);
ret ins.(0);
}
case (1u) {
// Only one incoming edge is live, so we just feed that block
// onward.
ret live.(0);
}
}
// We have >1 incoming edges. Make a join block and br+phi them into it.
auto join_cx = new_sub_block_ctxt(parent_cx, "join");
for (result r in live) {
r.bcx.build.Br(join_cx.llbb);
}
auto phi = join_cx.build.Phi(t, vals, bbs);
ret res(join_cx, phi);
}
impure fn trans_if(@block_ctxt cx, &ast.expr cond,
&ast.block thn, &option.t[ast.block] els) -> result {
@ -730,37 +766,22 @@ impure fn trans_if(@block_ctxt cx, &ast.expr cond,
auto then_cx = new_sub_block_ctxt(cx, "then");
auto then_res = trans_block(then_cx, thn);
auto next_cx = new_sub_block_ctxt(cx, "next");
then_res.bcx.build.Br(next_cx.llbb);
auto phi;
auto else_cx = new_sub_block_ctxt(cx, "else");
auto else_res = res(else_cx, C_nil());
alt (els) {
case (some[ast.block](?eblk)) {
auto else_cx = new_sub_block_ctxt(cx, "else");
auto else_res = trans_block(else_cx, eblk);
cond_res.bcx.build.CondBr(cond_res.val,
then_cx.llbb,
else_cx.llbb);
else_res.bcx.build.Br(next_cx.llbb);
phi = next_cx.build.Phi(T_nil(),
vec(then_res.val,
else_res.val),
vec(then_res.bcx.llbb,
else_res.bcx.llbb));
}
case (_) {
cond_res.bcx.build.CondBr(cond_res.val,
then_cx.llbb,
next_cx.llbb);
phi = next_cx.build.Phi(T_nil(),
vec(then_res.val, C_nil()),
vec(then_res.bcx.llbb,
cond_res.bcx.llbb));
else_res = trans_block(else_cx, eblk);
}
}
ret res(next_cx, phi);
cond_res.bcx.build.CondBr(cond_res.val,
then_res.bcx.llbb,
else_res.bcx.llbb);
// FIXME: use inferred type when available.
ret join_results(cx, T_nil(),
vec(then_res, else_res));
}
impure fn trans_while(@block_ctxt cx, &ast.expr cond,